1. Field of the Invention
This invention relates to mahole cover support and devices for increasing the height of the same to compensate for increased roadway height when resurfacing occurs.
2. Description of the Prior Art
Prior art devices have disclosed a number of different ways in which manhole covers can be raised by insertion of a variety of devices.
See for example U.S. Pat. Nos. 3,218,943, 3,891,337, 4,097,171 and 4,225,266.
A manhole cover support is disclosed in U.S. Pat. No. 3,218,943 having a plurality of vertically spaced circumferentially continuous teeth in a ring which is designed to selectively engage individual teeth which extend from a second part of the manhole cover. The arrangement allows the second part to support the manhole cover in adjusted vertical position at the time of insulation so as to match roadway surfacing material to be laid thereabout.
U.S. Pat. No. 3,891,337 discloses a one-piece split ring that has a single adjustment and locking bolt engaged in threaded openings in lugs positioned adjacent the ends of the split ring. The ring supports the manhole cover in elevated relation to its original position on a manhole cover support frame.
U.S. Pat. No. 4,097,171 shows a similar ring configuration with a two-piece toggle mechanism which when engaged in an over center position forces the ring outwardly locking the same in the manhole cover support frame.
Finally in U.S. Pat. No. 4,225,266, a method and apparatus is disclosed for raising manhole covers by a flanged split ring secured within the manhole cover support frame by an adjustable link, which after adjustment is hammered in place spreading the ring and locking the same in the manhole cover support frame.
Manholes are normally located in roadways or streets to allow access to underground sanitary and storm sewers and utility conduits. These manholes consist of an inverted belt-shaped metal frame supported by a brick or concrete base structure. The metal frame has an internal annular ledge for supporting a manhole cover which is lever with the top of the frame and the surrounding roadway surface. When resurfacing roadways, a layer of pavement is placed on the existing pavement resulting in the manhole cover being below the top surface of the new pavement causing a depression in the roadway. The common practice has been to elevate the manhole frame by removing the existing pavement around the manhole and increasing the support material with brick or concrete beneath the manhole frame and reasserting the frame on top of the supports. The raised frame is then repositioned and the roadway area abutting the manhole is replaced.
Applicant's invention uses a pair of split rings and clamps which are positioned on top of an existing manhole metal frame so as to increase the effective height of the same and particularly the internal annular ledge which supports the manhole cover. Combinations of split rings and clamps of applicant's invention provide a variety of height adjustment with the arrangement of the split rings forming a desirable annular configuration for receiving and holding the manhole cover at the desired increased height. The multiple rings are adjustable secured to the existing manhole metal frame and the roadway. The procedure can be performed in a short time at low cost and eliminates the problems heretofore associated with raising of the metal frames and the manhole cover supports thereby.